Surface-Water Routing (SWR) Process: A Program for Modeling Surface-Water Flow with the USGS Modular Groundwater Flow Model (MODFLOW)

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Overview of SWR Process

Cover image from SWR documentation showing example model grid.

Cover image from Surface-Water Routing (SWR) Process documentation showing example model grid.

The Surface-Water Routing (SWR) Process was developed to accurately simulate stages, surface-water flows, and surface-water/groundwater interactions in areas where surface-water gradients are small and (or) there is significant management of surface water. A simplified form of the Saint-Venant equations was implemented in the SWR Process based on assumption requirement that it will be applied to continuous simulations (hourly to daily time steps) in support of water-resource planning activities. As a result, the SWR Process was not intended as a replacement for hydrodynamic models that solve the full Saint-Venant equations and

are applied to event simulations (sub-hourly time steps).

The SWR Process uses a flexible approach for simulating one- and two-dimensional routing of surface-water flow. The SWR Process is implicitly coupled to the Groundwater Flow Process in MODFLOW. Surface-water routing in SWR can be simulated using a diffusive-wave approximation of the vertically-integrated Saint-Venant equations and/or a simplified level-pool approach. SWR can account for surface-water flow controlled by backwater conditions caused by small water-surface gradients or surface-water control structures. A number of typical surface-water control structures (such as culverts, weirs, and pumps, for example) can be represented, and simple operational rules can be specified to manage surface-water stages and streamflow by moving water from one surface-water feature to another. The non-linear surface-water flow equations implemented in the SWR Process are solved using Newton methods and

direct or iterative solvers.

The SWR Process uses the familiar structure of MODFLOW-2005 and the MODFLOW concepts of "packages" and "processes" are retained. This permits versions of MODFLOW-NWT and MODFLOW-2005 that include the SWR Process to work with many of the MODFLOW-related software programs, such as MODPATHZONEBUDGET, and parameter estimation programs. MODFLOW-NWT and MODFLOW-2005 with the SWR Process are public domain computer programs. The source code and software are distributed free of charge by the USGS.


Download Current Version of SWR Process

The current release is SWR Process v.1.01.0, released October 17, 2012.

Note: SWR Process users are encouraged to use the version incorporated into MODFLOW-NWT, even if the features of MODFLOW-NWT are not required for a particular application.


Documentation for SWR Process

Hughes, J.D., Langevin, C.D., Chartier, K.L., and White, J.T., 2012, Documentation of the Surface-Water Routing (SWR1) Process for modeling surface-water flow with the U.S. Geological Survey Modular Ground-Water Model (MODFLOW-2005): U.S. Geological Survey Techniques and Methods, book 6, chap. A40 (Version 1.0), 113 p.,


Programs Related to SWR Process


Superseded SWR Process Versions

Note: these versions are no longer actively supported or maintained.


Find MODFLOW-Related Software

Visit the MODFLOW and Related Programs page for a list of MODFLOW-related software.


Example USGS Applications of SWR Process

Hughes, J.D., and White, J.T., 2014, Hydrologic conditions in urban Miami-Dade County, Florida, and the effect of groundwater pumpage and increased sea level on canal leakage and regional groundwater flow: U.S. Geological Survey Scientific Investigations Report 2014-5162, 175 p.,

Hughes, J.D., Langevin, C.D., and White, J.T., 2014, MODFLOW-based coupled surface-water routing and groundwater flow simulation: Ground Water,


Software License and Purchase Information

This software is a product of the U.S. Geological Survey, which is part of the U.S. Government.


This software is freely distributed. There is no fee to download and (or) use this software.


Users do not need a license or permission from the USGS to use this software. Users can download and install as many copies of the software as they need.

Public Domain

As a work of the United States Government, this USGS product is in the public domain within the United States. You can copy, modify, distribute, and perform the work, even for commercial purposes, all without asking permission. Additionally, USGS waives copyright and related rights in the work worldwide through CC0 1.0 Universal Public Domain Dedication (